1. Field of the Invention
The invention in general relates to voltage probes for passing a test signal from an electronic circuit element to be tested to an oscilloscope or other electronic measurement device, and more particularly to such a probe that has multiple leads densely packed into a small area, certain of which leads are grounded. The invention also relates to a method of making such a probe with grounded leads.
2. Description of the Related Art
Voltage probes are commonly used to pass analog test signals from a circuit under test to an oscilloscope or other electrical or electronic test instrument. Such an electronic probe must be capable of passing an electrical signal on a node or pin of the circuit under test to the test instrument without distorting it, i.e. with high signal integrity. Further, it should not apply any voltage or current to the circuit under test. Present-day electronic circuits operate over frequencies from DC to several gigahertz. Thus, test probes capable of being used with a wide variety of circuits must be able to provide high signal integrity over a wide band width of frequencies.
Integrated and hybrid circuits are becoming both more complex and smaller, leading to ever higher numbers of package leads crowded into less and less space, that is, the leads are becoming extremely dense with very tight pitches. The parent application referred to above has essentially the same high density of circuitry as state-of-the-art integrated and hybrid circuits. The closeness of the individual leads in such high density circuits generally results in coupling between the leads and associated noise, distortion, etc. which is unacceptable in voltage probes. Thus, a probe that has a high density of leads yet in which the noise and coupling is virtually eliminated.
As will become evident below, the present invention solves the above problem in part by grounding all the leads of the probe that are connected to the pins of the circuit under test that are grounded. This usually results in a large number of grounded leads. Since the leads that are grounded are determined by the application of the probe, that is the particular chip to which a probe is applied this also results in a probe that is, in part, custom manufactured for its end application. It would be highly desirable to have a simple yet effective method of manufacturing probes with such customized grounded leads.
Voltage probes are sophisticated electronic instruments and thus are not inexpensive. Thus, it would also be highly desirable to have a voltage probe, the leads of which could be customizably grounded for its specific application, and, at the same time, could be still be used in many applications with little additional expense.